1. Field of the Invention
The present invention relates to an exchangeable continuous casting nozzle used for a slide nozzle device which pours molten metal such as molten steel into a casting mold, while controllably feeding the molten metal from a container such as a ladle and a tundish in a metal casting field.
2. Description of the Related Art
The slide nozzle device pours molten metal into a casting mold from a container for molten metal, e.g. a tundish. A conventional slide nozzle device is generally shown in FIG. 4. A conventional slide nozzle device attached to a bottom wall of the tundish comprises an upper nozzle 1 disposed on a bottom wall of the tundish, an upper fixed plate 2 supporting the upper nozzle 1 from below, a lower fixed plate 3, and a sliding plate 4 disposed between the upper fixed plate 2 and the lower fixed plate 3 and operated by a sliding means 5 to turn on/turn off the molten metal.
The slide nozzle device further comprises a collector nozzle 6 connected to the lower fixed plate 3 and an immersion nozzle 10 extending into a casting mold, and surrounded by a metal mantle 12, and a frame 18 uniting the above plates and nozzles in a body. These nozzles are made of various refractory materials. Further, a fixing flange 14 is fastened, through a metal supporting bar 13, to a metal casing 15 that surrounds the lower fixed plate 3. Fixing flange 14 unites the lower fixed plate 3, the collector nozzle 6, and the immersion nozzle 10 in a body. Arms 16 disposed beneath the frame 18 mounting the sliding means 5 fix the lower fixed plate 3, the collector nozzle 6, and the immersion nozzle 10, all of which are united in the frame 18.
The molten metal in the container passes through a through hole 1A of the upper nozzle 1, a through hole 2A of the upper fixed plate 2, a through hole 4A of the sliding plate 4, a through hole 3A of the lower fixed plate 3, a through hole 6A of the collector nozzle 6, and a through hole 10A of the immersion nozzle 10, and then it is poured into the casting mold (not shown).
The conventional slide nozzle device has a problem that the air is entrapped into the through holes through seams between the lower fixed plate 3 and the collector nozzle 6, and between the collector nozzle 6 and the immersion nozzle 10, thereby causing the molten metal to be oxidized, which deteriorates the quality of the molten metal.
The reasons for the above problem are given in details as follows:
(1) Mortar disposed in the seam between the collector nozzle 6 and the immersion nozzle 10 deteriorates in plasticity due to heat of the molten metal passing through the through holes inside the nozzles.
(2) The metal supporting bar 13 fastening the fixing flange 14 is subjected to thermal expansion, thereby decreasing the fastening force of fastening the lower fixed plate 3, the collector nozzle 6, and the immersion nozzle 10.
(3) The fastening force due to the metal supporting bar 13 and the bending moment caused at replacing the nozzle, etc., causes the mating faces of the collector nozzle 6 and the immersion nozzle 10 to be broken. Furthermore, the slide nozzle device has other problems related to the time required to unite the collector nozzle 6 and the immersion nozzle 10, and to the economical efficiency such as the manufacturing cost.
Therefore, in order to solve the above-mentioned problems, a Japanese Provisional Patent Publication (Kokai) No. 6-13457 has disclosed, as shown in FIG. 5, an integral nozzle 30 in which the lower fixed plate, the collector nozzle and the immersion nozzle are integrated with one another in a body. The integral nozzle 30 comprises a tube body 32 made of a refractory material and a flange portion 33 contacting to the sliding plate. An upper part of an inner circumferential portion of the tube body 32 and an upper face of the flange portion 33 are formed with an insert portion 34 made of a wear-resistant and greater hardness refractory material, and then the flange portion 33 is surrounded by a metal casing 35.
This integral nozzle eliminates the need for using mortar in the seam between the collector nozzle and the immersed nozzle, etc., which solves the problem of oxidizing the molten metal due to lowering of the sealing property. Further, a metal mantle, bolts and nuts required to unite the collector nozzle and the immersion nozzle can be eliminated, which brings about the resolution of the problems related to the manufacturing cost and time.
However, the existent continuous casting nozzles are clogged during long time use, which requires a frequent replacement of the nozzle. Further, the replacement must be carried out quickly in order to increase the efficiency, which causes the bending stress to be applied in a direction to replace the nozzle.
In the integral nozzle 30 disclosed in Japanese Provisional Patent Publication (Kokai) No. 6-13457, since the whole integral nozzle 30 is made of a refractory material, the performance of the sealing property is improved and further the total length of the nozzle is increased. However, it has other problems related to not only the transportation and the handling, but also occurrence of the breakage due to the weak strength against the bending stress in a direction to replace the nozzle. Moreover, the above-mentioned nozzle should be replaced more frequently, which requires quickness of the replacing work, improvement of the safety, and easiness of replacing the nozzle.
It is therefore an object of the invention to provide a continuous casting nozzle used for a slide nozzle device, which is capable of being easily transported and being quickly and safely replaced, and further is not easily damaged on handling, particularly, on replacing.
To attain the above object, the inventor has paid a keen attention to reinforcing of a continuous casting nozzle, conjunction between a metal casing portion surrounding a flange portion and a metal skirt portion surrounding a tube body, and thereby have invented the following:
The present invention provides an exchangeable continuous casting nozzle to be used in a slide nozzle device, comprising:
(a) a nozzle including a flange portion made of a refractory material having a through hole for receiving molten metal flowing out of the upper nozzle, and a tube body of a refractory material, continuing from the flange portion and having another through hole continuing from the through hole, and
(b) a metal protecting body including a metal casing portion surrounding the flange portion, a metal skirt portion surrounding an upper portion of the tube body, and metal reinforcing portions disposed around a junction between the metal casing portion and the metal skirt portion in parallel with a direction to detach/attach the nozzle for reinforcing.
The exchangeable continuous casting nozzle has the metal reinforcing portions on the connecting portion of the metal casing portion and the metal skirt portion in parallel with the nozzle attaching/detaching direction; therefore, quick replacement of the integral nozzle prevents the nozzle from being broken at a connecting at portion between the flange portion and the tube body.
Preferably, the metal reinforcing portion comprises a reinforcing portion shaped like a half rectangular in horizontal section, fixed to the metal casing portion and the metal skirt portion from the outside.
This metal reinforcing portion is simple in contour, which ensures easy working and a sufficient strength of the metal reinforcing portion.
Preferably, the metal reinforcing portion comprises a reinforcing portion having a curved portion which is identical in curvature with the metal skirt portion, and a plate-like portion connected to the curved portion, the reinforcing portion being fixed to the metal casing portion and the metal skirt portion from the outside.
This metal reinforcing portion is complicated in contour; however, preliminarily preparing parts enables the parts to be easily welded, and so on.
Preferably, the metal reinforcing portion comprises a reinforcing portion having a curved portion which is shaped like a circle or polygon in horizontal section, and a bar-like member, the reinforcing portion being fixed to the metal casing portion and the metal skirt portion from the outside.
This metal reinforcing portion is simple in contour, which ensures easy working and a sufficient strength of the metal reinforcing portion.
Preferably, the metal reinforcing portion comprises a reinforcing portion shaped like a crescent in horizontal section, fixed to the metal casing portion and the metal skirt portion from the outside.
This metal reinforcing portion is complicated in contour; however, preliminarily preparing parts enables the parts to be easily welded, and so on.
Preferably, the metal reinforcing portion comprises a reinforcing portion shaped like a triangle in vertical section, fixed to the metal casing portion and the metal skirt portion from the outside.
This metal reinforcing portion is simple in contour, which ensures easy working and a sufficient strength of the metal reinforcing portion.
Preferably, the metal reinforcing portion comprises a reinforcing portion shaped like a deformed pentagon in vertical section, fixed to the metal casing portion and the metal skirt portion from the outside.
This metal reinforcing portion is simple in contour, which also ensures easy working and a sufficient strength of the metal reinforcing portion.
More preferably, the flange portion comprises at least two refractory material layers of a lower layer and an upper layer, the lower layer being made of the same refractory material as the tube body, and the upper layer being made of a refractory material which is greater in hardness than the tube body.
It is preferable that an upper face of the flange portion contacts to the lower fixed plate or the sliding plate which is greater in hardness, and that it is greater in hardness than the tube body so as not to be eroded by the flowing molten metal.
Further preferably, the flange portion is preferably made of three refractory layers of a lower layer, an intermediate layer, and an upper layer, the lower layer being made of the same material as the tube body which is less in hardness, and then the intermediate layer and the upper layer are made of materials which become greater in hardness in order than the tube body.
The intermediate layer has an intermediate hardness between those of the tube body and the upper layer, which prevents the lower layer and the upper layer from being separated due to the difference between the thermal expansion thereof.
Further advantages of the invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.